Conventionally, there are provided data processing devices as various electronic devices such as personal computers and smart phones. Some of these data processing devices include a digital data processing unit that processes high-capacity digital data such as image data and music data. On a personal computer, for example, the digital data processing unit may operate abnormally. In such case, a user can press a reset button to reset the digital data processing unit (and recover from the error).
For example, a vehicle may be mounted with the data processing device such as a vehicle navigation system. In this case, the reset manipulation may interrupt driver's concentration on driving every when the driver is required to perform the manipulation to recover the digital data processing unit that operates abnormally. As a reset method, patent literature 1 discloses the configuration of providing a monitoring microcomputer to monitor a microcomputer. According to this configuration, the monitoring microcomputer monitors whether or not the microcomputer operates abnormally. When an error occurs, the monitoring microcomputer resets the abnormal operation of the microcomputer.
The method disclosed in patent literature 1 can reset an abnormal operation of a microcomputer without a user's reset operation. However, the digital data processing unit including a user interface function may, for example, disable acceptance of manipulation made by a user or disable switchover of display windows while the abnormal operation of the digital data processing unit being reset. Thus, during the reset operation of the digital data processing unit, user interface function is disabled temporarily.